Ain't a goddamn chance Cait Sith would have willingly betrayed Winter. Dude almost fought his way back from Nemesis on the boat at the end of Cold Days, duty is his lifeblood.
I'm not so about that. He seems to actively goes out to obey Dresden's orders in the most malicious way possible. He continuously states how much he hates working for Dresden, and to me at least seems to only be willing to work fore Dresden as he is obliged to.